1. Field of the Invention
This invention relates to novel amide derivatives and dermatologic preparations containing the same. More particularly, it relates to dermatologic preparations capable of fundamentally improving the barrier functions of the horny layer, namely, exerting effects of maintaining normal barrier functions and restoring damaged barrier functions.
2. Description of the Prior Art
The skin, in particular, the horny layer is an extremely thin epidermic constituent which is located on the outermost side of the body. It not only protects the body from external irritation and invasion of foreign substances but also inhibits the loss and evaporation of the constituents and moisture contained in the body. Those protecting effects, i. e. , the barrier functions of the horny layer are important in controlling the homeostasis in the physiological functions of the skin.
When these barrier functions of the horny layer are weakened by some internal or external reasons, for example, the skin frequently suffers from troubles such as inflammation, chapping or the acceleration of aging. Therefore, it is needless to say that the maintenance and reinforcement of the barrier functions of the horny layer are highly important for the skin and, in its turn, for our healthy daily life.
To prevent the occurrence of these skin troubles or to remedy the same, there have been employed dermatologic preparations containing various natural and synthetic ingredients. However, most of these dermatologic preparations aim at humidifying the skin and making up for the barrier functions by forming a coating on the surface of the skin. Namely, these dermatologic preparations merely make up for the barrier functions of the skin by forming a temporary coating on the surface of the skin. Thus they cannot be expected too much in the effects of essentially improving (maintaining and restoring) the barrier functions.
Thus, the present applicant has formerly proposed dermatologic preparations containing amide derivatives represented by the following general formula as dermatologic preparations capable of essentially improving the barrier functions of the skin (see Japanese Patent Laid-Open No. 306952/1990). Further, Scott et al. have proposed cosmetic compositions containing amide derivatives of similar structures (see Japanese Patent Laid-Open No. 225907/1992). Although these amide derivatives act on the horny layer and thus exert effects of essentially improving the barrier functions of the skin, the application of them to dermatologic preparations still involves some problems relating to the solubility in bases and oxidation stability. ##STR2## (wherein R.sup.1 represents a straight-chain or branched, saturated or unsaturated hydrocarbon group carrying 10 to 40 carbon atoms; R.sup.2 represents a straight-chain or branched hydrocarbon group carrying 3 to 39 carbon atoms; and R.sup.3 represents a hydrogen atoms, a straight-chain or branched, saturated or unsaturated hydrocarbon group carrying 10 to 40 carbon atoms or an acyl group).